1. Field of the Invention
The invention relates to a manipulator serving particularly to position a test head. The manipulator comprises positioning means for three-dimensionally positioning a test head. In addition, the manipulator is provided with a mount for the test head. The mount comprises a rotary guide by means of which the test head is rotatable about an axis of rotation. The rotary guide comprises a mounting plate connected to the positioning means and a supporting plate rotatable relative to the mounting plate about the axis of rotation, the test head being securable to the supporting plate. Mounting plate and supporting plate have concentric openings for receiving a connecting cable connecting the test head.
2. Background Art
Such a manipulator usually has several degrees of translatory and rotational motion in being suitable for precisely three-dimensionally positioning a test head as required as a rule in the testing of electronic devices, such as, for example, ICs or wafers. For function testing electronic devices the relatively heavy test head needs to be precisely docked on a tester such as, for example, a device handler or wafer prober, furnishing the devices to be tested by the test head. Obtaining a genuine test result in testing the devices necessitates precise docking of the test head on the handler. This is why smooth, precise adjustment of the manipulator positioning the test head is mandatory
One such manipulator of the aforementioned kind is described in German patent DE 40 07 011. Known furthermore from DE 101 32 489 A1 is a manipulator having precise replication in moving the test head by the positioning means comprising articulated arms pivotable in the horizontal plane coupled to horizontally travelling carriages. This achieves optional motion of the test head being split into translatory motion of the carriages and rotational motion of the articulated arms, resulting in a reproducible motion of the test head ensuring reliable docking of the test head on a handler.
A manipulator for positioning a test head on a handler is also disclosed as a test head robot in EP 0 308 348 B1. This manipulator has a rotary guide permitting rotation of the test head about an axis of rotation. The rotary guide comprises a circular supporting plate to which the test head is securable. The supporting plate is rotationally disposed in a mounting ring composed of a lower arcuate member and an upper arcuate member. The lower arcuate member is held stationary, whereas the upper arcuate member is located pivotable on the lower arcuate member. Opening up the upper arcuate member permits insertion of the supporting plate into the mounting ring. Pivoting the upper arcuate member into the closed position then locks the upper arcuate member to the lower arcuate member by locking means, so that the supporting plate is rotatably clamped in the mounting ring. The supporting plate is provided furthermore with openings through which a connecting cable can be inserted for connecting the test head.
Even though being able to open up the mounting ring facilitates clamping in place the supporting plate, the rotary guide of the known manipulator has proven to be unsatisfactory for installing and removing the test head. This is because the connecting cable, for sensing reasons, is as a rule non-releasably connected to the test head, thus requiring the free end of the connecting cable to be pulled through the opening in the supporting plate when securing the test head to the supporting plate. Pulling the connecting cable through the opening in the supporting plate is additionally made more difficult because the connecting cable, as a rule, is relatively thick and comparatively inflexible.